Routing table management method using interface ID in the IPv6

ABSTRACT

A routing table management method using an interface ID in the IPv6 that supports RIPng (Routing Information Protocol for next generation), prevents congestion in routing table management because multiple addresses are designated to a single interface, through managing a routing table using a different interface ID for each IPv6 router interface. According to the routing table management method, a first router designates a predetermined value to a first field of a route entry, designates an interface ID to a second field, thereby generating routing information, and a routing information packet including the routing information is transmitted to a second router. Then, the second router extracts a first field value of the received routing information packet from the first router and if the extracted field value is a predetermined value, a second field value is extracted therefrom. Lastly, routing information of a route entry having an interface ID identical with the extracted second field value is updated to routing information of the received routing information packet.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, andclaims all benefits accruing under 35 U.S.C. §119 from an applicationfor ROUTING TABLE MANAGEMENT METHOD USING INTERFACE ID IN THE IPv6earlier filed in the Korean Intellectual Property Office on 22 Nov. 2002and there duly assigned Serial No. 2002-73232.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a routing table management method usingan interface ID (identification) in the IPv6 (Internet Protocol version6), and more particularly, to a routing table management method using aninterface ID in the IPv6 that supports a RIPng (Routing InformationProtocol for next generation), to prevent congestion in routing tablemanagement because of a multisource address, through managing a routingtable using a different interface ID for each IPv6 router interface.

2. Description of the Related Art

Internet standard protocol, TCP/IP (Transport Control Protocol/InternetProtocol) of a computer, like other network protocols, has layeredstructure called protocol stack, protocol suite or simply protocolstructure.

The TCP/IP protocol stack has two very important infrastructures, namelyTCP and IP. The IP protocol corresponds to an OSI (Open SystemsInterface) layer 3, and IPv4 is one of the most popular versions now. Itis usually used to connect physical subnetworks and select a route to adestination IP address.

To this end, the IP protocol provides source addresses and destinationaddresses of a number of internetworked terminals and nodes and doesinterpretation. The Internetwork layer being currently used employs a32-bit IP address for intercommunication between hosts over a network.IP address distinguishes a specific node by using a network IP and anode IP (host IP).

As there has been an explosive increase in Internet use since 1990's, itbecame necessary to improve some weaknesses in the IPv4, including ashortage of allocable resources, lack of mobility, lack of security andso forth. To overcome these shortcomings, a new standard protocol, IPv6,was developed.

The IPv6, also called IPng (Internet Protocol next generation), is welldescribed in RFC (Request for comments) 2460 standard document.Extending the length of an IP address from an existing 32 bits to 128bits, the IPv6 protocol resolved the problem with the deficiency ofInternet address resources, and provided a way to process multimediadata in real time. Unlike the IPv4 protocol in which a patch typeprotocol IPsec (Internet Protocol Security Protocol) was installedseparately, the IPv6 protocol mounted the IP sec onto the protocoldirectly, thereby fortifying a security function even more.

However, IPv6 protocols and IPv4 protocols are not compatible to eachother because their header structures are different. Supposedly in thenear future IPv4 network will be replaced to one that can support IPv6network or both the IPv4 and the IPv6 at the same time. In addition, theIPv6 protocol has been gradually expanding its application range throughdiverse test networks and part of commercial networks.

An IPv6 application TCP/IP standard protocol is composed of anapplication layer, a transport layer implemented of TCP or UDP (UserDatagram Protocol), Internetwork layer implemented of IPv6 and/or ICMPv6(Internet Control Message Protocol for IPv6), and a physical layer.

IPv6 Datagram, similar to the IPv4, is composed of two parts: Header andPayload. The payload transmits data between two hosts. IPv6 header has afixed length of 40 bytes, and does not have a header checksum field thatis known as a serious bottleneck phenomenon in the IPv4 protocol. Morespecifically, the header structure of the IPv6 protocol, unlike in theIPv4 protocol, is capable of supporting mobility and security, andproviding quality assurance of the multimedia applications.

As for basic header fields of the IPv6 standard protocol, a 4-bitversion field, an 8-bit traffic class field, a 20-bit stream label fieldin connection with QoS (Quality of Service), a 16-bit unsigned integerpayload length field, an 8-bit NH (Next Header) defining type of a nextheader in the IPv6 header, an 8-bit unsigned integer hop field thatdecreases by ‘1’ each time from respective nodes forwarding a packet, asource address field representing a 128-bit address of a packet sender,and a destination address field representing a 128-bit address of apacket receiver.

Expanded header fields for implementing IPv6 more perfectly include ahop-by-hop option field, a destination option header, a routing header,a fragment header, an authentication header, an ESP (EncapsulatingSecurity Payload) header and so on.

This type of IPv6 protocol is usually implemented in the form ofsoftware for PCs (personal computers). In general, it is adaptive tooperating systems like WINDOWS, LINUX, REAL-TIME, or OS.

On the other hand, routing protocols can be divided into two kinds,namely IGP (Interior Gateway Protocol) and EGP (Exterior GatewayProtocol).

The IGP is a routing protocol used in one domain. Typical IGP protocolsbeing currently used in the IPv4 include RIP (Routing InformationProtocol), OSPF (Open Shortest Path First), IS-IS (Intermediate Systemto Intermediate System) and so forth.

The EGP is usually used for exchanging routing information betweendifferent domains, especially between ASs (autonomous systems). One ofthe typical EGP protocol for use in the IPv4 is BGP (Border GatewayProtocol).

The IGP transmits routing information within an AS while the EGPtransmits routing information among more than one ASs.

In fact in a theoretical sense, the IPv6 routing technology is not muchdifferent from an existing IPv4 except that the IPv6, compared to theIPv4, sets forth more strict regulations on IPv6 addressing, e.g. routeaggregation, and for this, an appropriate routing protocol should bedesignated and operated.

The following describes routing protocols supporting an alreadystandardized IPv6 or an IPv6 in progress of standardization:

-   -   IGP protocols for use in IPv6        -   RIPng        -   OSPFv6        -   IPv6 or IS-IS    -   EGP protocol for use in IPv6        -   BGP4+

RIP is the most frequently used IPv6 protocol implemented with adistance vector base algorithm.

Its definition was first given in 1988, and standardized by RFC 1058.

As aforementioned, the RIP is a protocol based on a distance vectoralgorithm. The protocol itself is very simple and was originallydesigned for small and medium sized networks. However, it has severaldefects as follows:

First, the longest route of the RIP is limited to a 15-hop network;

Second, the RIP undergoes a process called “counting unto infinity” forthe purpose of solving a routing loop problem. Unfortunately thisprocess consumes a great amount of network resources even before solvingthe problem; and

Third, the RIP does not consider real time parameters, e.g. delay,reliability or load, but uses a fixed measurement standard to comparealternate routes.

Following RFC 1723 (RIPv2), RFC 2080 (IPv6 supporting RIPng standard)defines the RIP protocol.

Although many algorithms for selecting an optimum source address arebeing studied to prevent the RIPng router from taking improper actions,the algorithms are all about selecting one of multiple addresses anddesignating it as a source address. Thus, if the source address ischanged when selecting one according to the algorithm, the RIPng routeris ended up with congestion again.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide arouting table management method using an interface ID in the IPv6,capable of preventing a congestion phenomenon that occurs when managinga routing table with multiple source addresses designated for the IPv6router interface supporting RIPng (Routing Information Protocol for nextgeneration).

It is another object to provide an apparatus and technique forpreventing routing problems caused by designating multiple link-localIPv6 addresses to one interface.

It is yet another object to provide an apparatus and technique thatprevents the routing problem at an application level in a defaultaddress selection mechanism.

It is still yet another object to provide an apparatus and techniqueaccording to the present invention that as long as a physicalinterface's own ID is used, the RIPng can be applied independent ofsource addresses even when routing congestion is controlled at a lowerlevel than an application level.

To achieve the above and other objects, there is provided a routingtable management method applicable to a network having a plurality ofrouters and a plurality of hosts, the method including: a first step, inwhich a first router designates a predetermined value to a first fieldof a route entry, designates an interface ID to a second field, therebygenerating routing information, and a routing information packetincluding the routing information is transmitted to a second router; asecond step, in which the second router extracts a first field value ofthe received routing information packet from the first router and if theextracted field value is a predetermined value, a second field value isextracted therefrom; and a third step for updating routing informationof a route entry having an interface ID identical with the extractedsecond field value to routing information of the received routinginformation packet. Here, the interface ID designated to the secondfield can be generated using a MAC Address (Media Access Controladdress).

In addition, the first step includes the sub-steps of: extracting, atthe first router, an interface ID from interface information;designating, at the first router, a predetermined value to the firstfield of the route entry; designating, at the first router, theextracted interface ID to the second field of the route entry;generating a routing information packet including the first field withthe predetermined value, the second field with the designated interfaceID, and routing information; and transmitting, at the first router, thegenerated routing information packet to the second router.

Also, the third step includes the sub-step of: deciding whether therouting table has a route entry having an interface ID identical withthe second field, and if the routing table has the route entries havingthe identical interface IDs, updating routing information of the routeentry to routing information of the received routing information packet,but if the routing table does not have route entries with the identicalinterface IDs, designating the interface value of a source router to areceived interface ID and generating a route entry using the routinginformation of the received routing information packet.

Preferably, an IGP (Interior Gateway Protocol) or RIPng (RoutingInformation Protocol for next generation) is used for a routing protocolbetween the first router and the second router.

The first field is a metric designation field, and the second field is aprefix field. Moreover, the metric designation field takes one value outof a range 17-255.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings in which likereference symbols indicate the same or similar components, wherein:

FIG. 1 is a diagram illustrating a RIPng routing table of a related art;

FIG. 2 is a diagram illustrating multiple source addresses designated inan IPv6 router interface of a related art;

FIG. 3 is a diagram showing a connection state of a plurality of routersto which the present invention is applied;

FIG. 4 a depicts a general RIPng packet format;

FIG. 4 b depicts a router table entry format;

FIG. 5 is a diagram illustrating a modified RIPng routing tableaccording to the present invention;

FIG. 6 is a flow chart showing a generation and transmission procedureof a packet with routing information on a transmitting router accordingto a preferred embodiment of the present invention; and

FIG. 7 is a flow chart showing how to process a received packetincluding routing information of a receiving router according to anotherpreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings, to see an IPv6 routing table entry undermanagement of the RIPng with reference to FIG. 1, the entry shouldinclude information on an IPv6 prefix 10 of a destination, a metric 16for displaying a total cost needed to transmit Datagram to thedestination, an IPv6 address 24 of a next router representing a nexthop,a route change flag 18 for informing whether a router has recently beenchanged, and a 30-sec (second) timer 20 and 22 for transmitting routingtable information to a neighbor router.

The RIPng is a UDP base protocol, and transmits/receives a packet on aUDP port number 521. A RIPng packet includes three fields, i.e. acommand (request or reply), version and routing table entry.

Also, each route table entry includes an IPv6 prefix 10, a route tag 12for separating an interior router from an exterior router, a prefixlength field 14 for deciding important bits in the prefix, and a meter16 for defining a present destination meter.

Further, the RIPng shows a nexthop IPv6 address for a packet. Thenexthop is designated through a RTE (Route Table Entry) packet and anexthop RTE.

A nexthop RTE packet is distinguished by a FFH value in a metric field.The length of route tag and prefix are set to zero when transmitting apacket and disregarded when receiving a packet.

The nexthop of the RIPng may or may not be expressed in the nexthopfield of a received RIPng packet.

In general, the nexthop is set to 0:0:0:0:0:0:0:0, and when the nexthopof the received RIPng packet is 0:0:0:0:0:0:0:0, the address of apacket-transmitted router is designated as the address of the nexthop.

If the nexthop address is known, it has to be a link-local address allthe time.

This is because when an IPv4 base RIP is designed, the RIPng is designedto the IGP so its data is valid only over a directly-connected networkand used in the link-local scope.

In other words, the IPv6 source address of Datagram in the RIPng has tobe a link-local address always.

RIPng version 1 supports two commands, request and reply. The requestcommand is used when requesting part or the entire routing table. Inmost cases, the request is transmitted as a multicaster from the RIPng(port 521).

There are three types of reply command, including a reply to a specificinquiry, a regular update being transmitted to every neighbor routerevery 30 seconds, and an update for causing changes in a router.

Definitions of request and reply packet processing are defined in RFC2080 and RFC 2081, respectively.

According to RFC 2080, when generating a reply message in the RIPng, theIPv6 source address should be a transmitting router interfaceablelink-local address all the time except when the reply message is ananswer for a unit cast request message of another port other than theRIPng port.

In case the reply is for the unit cast request message, the sourceaddress should be a globally valid address.

Moreover, the router interfaceable link-local address was used for theIPv6 source address because on receiving the reply message, thereceiving router uses the source address for the nexthop.

If the receiving router uses a wrong source address, the other routercannot route the datagram.

Sometimes, the router uses a plurality of IPv6 addresses as an addressfor one physical interface.

This means that a number of logical IPv6 networks can be implemented bya single physical medium.

It is also possible that a router uses a plurality of link-localaddresses for one physical interface.

FIG. 2 illustrates a multiple source address designated in a generalIPv6 router interface. As shown in the drawing, a multiple global IPv6addresses or multiple link-local IPv6 addresses can be designated for anIPv6 router interface.

Referring to FIG. 2, the multiple link-local IPv6 addresses aredesignated in an IPv6 router interface eth0, and the multiple globalIPv6 addresses are designated in an IPv6 router interface eth1.

In like manner, multiple source addresses are designated in an IPv6router interface to find a most efficient route to a destination byusing an optimal address among many source addresses and destinationaddresses.

In fact, methods for selecting optimal source address and destinationaddress are being actively developed.

On the other hand, when a router uses a plurality of link-localaddresses for one physical interface, the router must generate a replymessage using one of link-local addresses defined for interface as asource address.

Also, when a local address being currently used is not valid, theinvalid local address should be replaced to another local address.

This exchange is necessary for a receiving a node that received thereply message to distinguish a transmitting side based on the sourceaddress.

If the router receives a multipacket using another source address fromthe same router, the router decides that the multipacket is sent from adifferent router and takes an improper action.

That is, if a plurality of packets from the same router use differentsource addresses for link-local addresses, respectively, the RIPngrouter when receiving the packets decides that those packets are fromdifferent routers.

Moreover, when a router transmits a packet with a network prefix afterdesignating a new link-local address as a source address because thelink-local address having been used is no longer valid, a receivingrouter decides that the packet is from another router.

For instance, suppose that a R1 router uses a link-local addressfe80::1:2:3:4/10 designated in an I1 interface as a source address andtransmits routing information regarding 10.0.0.0/8 with metric 3 to a R2router. Then, the R1 router selects a fe80::5:6:7:7/10 as a new sourceaddress during a next update cycle because the address fe80::1:2:3:4/10is no longer valid, and transmits an update packet-regarding 10.0.0.0/8to the R2 router, having changed the metric to 5.

At this time, the R2 router decides that the previously transmittedrouting information and the routing information transmitted later aresent from different source routers, and performs a decision processingtherefor.

As a result, the routing information received for the second time, ofwhich metric is 5 and prefix is 10.0.0.0/8, is disregarded. In short,the IPv6 router, as it uses multiple link-local addresses, can causecongestion in source address selection, and the receiving router caninclude wrong routing information in its routing table.

Although many algorithms for selecting an optimum source address arebeing studied to prevent the RIPng router from taking improper actions,the algorithms are all about selecting one of multiple addresses anddesignating it as a source address. Thus, if the source address ischanged when selecting one according to the algorithm, the RIPng routeris ended up with congestion again.

The following detailed description will present a routing tablemanagement method using an interface ID in the IPv6 according to apreferred embodiment of the invention in reference to the accompanyingdrawings.

FIG. 3 shows how a plurality of routers are connected to each other,including a plurality of IPv6 routers RA (Router A)˜RE (Router E)mounted with an interface having multiple link-local IPv6 addresses anda modified RIPng, and a plurality of IPv6 hosts HA (Host A) and HB (HostB) that are connected to the plural routers RA˜RE. The routers RA˜RE andthe hosts HA and HB should be set up over the same network.

When the source routers RA˜RE mounted with the modified RIPng transmit apacket including routing information to neighbor routers RA˜RE, theytransmit interface IDs in replacement of source addresses.

Each interface has its own ID. Even though multiple link-local IPv6addresses could be designated in one interface, there is only oneinterface ID because it is generated by using MAC Address. The presentinvention illustrated Ethernet using MAC Address to generate aninterface ID out of convenience, but other links can also generateinterface IDs, following the relevant standards therefor. For example,in case of ATM (Asynchronous Transfer Mode), the standard is shown inRFC2492. In like manner, RFC2470 defines a standard for token ringnetwork, RFC2590 for FrameRelay, RFC2467 for FDDI (Fiber DistributedData Interface0, and RFC2491 for NBMA (Non Broadcast Multi Access).

Turning back to FIGS. 1 and 2, there were two link-local addresses ofthe interface eth0. Particularly, ‘fe80’ out of‘fe80::204:76ff:fe6f:7c1;f/10’ is a prefix address and the rest‘204:76ff:fe6f:7c1f/’ is an interface ID.

FIG. 4 a shows a general RIPng packet format, and FIG. 4 b shows arouter table entry format.

As shown in FIG. 4 a, the general RIPng packet format is composed of acommand 30, a version 32, and a plurality of route table entries 40 a˜40n. The route table entries 40 a 40 n include an IPv6 prefix 50, a routetag 52, and a metric 56. Each route table entry also includes a prefixlength field 54.

Since only one interface ID is needed as the replacement of a sourceaddress, if a metric value of the RIPng packet is 0×FF, the interface IDis designated in the prefix 50. The metric value for 0×FF can be 1 byte.In the present invention, the metric value ranges are 17˜255 because0˜16 are already being used. Particularly, the value 255 out of theavailable range is chosen.

On the other hand, the routing table for routers RA˜RE mounted with amodified RIPng should have an interface ID field to store interface IDsfor the source routers RA˜RE. FIG. 5 illustrates the structure of arouting table for the modified RIPng having a separate interface IDfield.

As shown in FIG. 5; the routing table for the modified RIPng is composedof an IPv6 prefix 60 of a designation, a metric 66 for representing adistance to the designation, a flag 68, timers 70 and 72, a nextrouter's IPv6 address 74 representing a nexthop, and additionally aninterface ID field 76 for storing interface IDs. Each route table entryalso includes a route tag 62 and a prefix length field 64.

Receiving a packet including routing information, the router RA˜REmounted with the modified RIPng checks the received packet to seewhether there is a route table entry with a metric value of 0×FF, and ifso, stores a prefix field value in the interface ID field 76 of thepacket source router RA˜RE because the interface ID must have beenstored in the prefix 60.

When processing the route entry, the router RA˜RE compares interface IDsto each other, and if they are identical, decides that the route entryis sent from the same source router RA˜RE because, as aforementioned,the interface ID is a specific value for each interface.

If the source addresses of a received packet are different from eachother, the router RA˜RE compares interface IDs, and if the interface IDsare identical, decides that the same source router RA˜RE transmitted theentry. The previous nexthop of the routing table is updated to a newsource address.

In addition, when searching a routing table, it is recommended to searchentries with the same interface ID and then select a correspondingprefix. At this time, the source address does not need to be searchedout.

This is because when the interface IDs are identical, the route entryinformation is transmitted from the same router RA˜RE although sourceaddresses might be different from each other.

FIG. 6 is a flow chart showing a generation and transmission procedureof a packet with routing information on a transmitting router accordingto a preferred embodiment of the present invention.

As illustrated in FIG. 6, the transmitting router extracts an interfaceID from the interface information (S100), and when generating a packet,designates 0×FF value to the metric field of the highest-level routeentry (S102), indicating that an interface ID has been given to theprefix of the route entry.

Next, the transmitting router designates an interface ID to the prefixof the route entry where 0×FF value is being set up in the metric field(S104), and completes packet generation following the known RIPng packetgeneration method (S106), and transmits the generated RIPng packet toanother router (S108).

FIG. 7 is a flow chart showing how to process a received packetincluding routing information of the receiving router according toanother preferred embodiment of the present invention.

As illustrated in FIG. 7, upon receiving the RIPng packet (S210), thereceiving router decides whether the metric field value of the routeentry is 0×FF (S212).

If it turns out that the metric field value is not 0×FF value, thereceiving router performs the process of the existing RIPng (S214), andif the metric field value is 0×FF value, meaning that the interface IDof the source router has been designated to the prefix field, thereceiving router extracts a prefix value (S216) and decides whetherthere exists a routing table having the same interface ID (S218).

If there is a routing table with the identical interface ID, thereceiving router updates the routing table (S220). However, if there isno such routing table having the identical interface ID, the receivingrouter stores the extracted prefix value as the interface ID of thesource router (S222).

So far the RIP (Routing Information Protocol) has been described as arouting protocol for IPv6, but it is also applicable to the IGP(Interior Gateway Protocol) for use in small-sized networks, such as,OSPF and IS-IS.

In conclusion, the present invention can be advantageously used forsolving a possible routing problem caused by designating multiplelink-local IPv6 addresses to one interface.

Moreover, although further discussions should be made continuouslywhether to solve the routing problem at an application level in adefault address selection mechanism, according to the present invention,as long as a physical interface's own ID is used, the RIPng can beapplied independent of source addresses even when routing congestion iscontrolled at a lower level than an application level.

While the invention has been described in conjunction with variousembodiments, they are illustrative only. Accordingly, many alternative,modifications and variations will be apparent to persons skilled in theart in light of the foregoing detailed description. The foregoingdescription is intended to embrace all such alternatives and variationsfalling with the spirit and broad scope of the appended claims.

1. A routing table management method applicable to a network having aplurality of routers and a plurality of hosts, the method comprising:designating, by a first router, a predetermined value to a first fieldof a route entry, and designating, by the first router, an interfaceidentification to a second field, accommodating a generating of routinginformation, and a routing information packet including the routinginformation being transmitted to a second router; extracting, by thesecond router, a first field value of the received routing informationpacket from the first router and when the extracted field value is thepredetermined value, a second field value is extracted therefrom; andupdating routing information of a route entry having an interfaceidentification identical with the extracted second field value torouting information of the received routing information packet.
 2. Themethod according to claim 1, wherein the interface identificationdesignated to the second field is generated using a media access controladdress.
 3. The method according to claim 1, wherein the step ofdesignating by the first router comprises the sub-steps of: extracting,at the first router, an interface identification from interfaceinformation; designating, at the first router, the predetermined valueto the first field of the route entry; designating, at the first router,the extracted interface identification to the second field of the routeentry; generating a routing information packet including the first fieldwith the predetermined value, the second field with the designatedinterface identification, and routing information; and transmitting, atthe first router, the generated routing information packet to the secondrouter.
 4. The method according to claim 1, wherein the step of updatingrouting information of the route entry comprises the sub-steps of:deciding whether the routing table has a route entry having an interfaceidentification identical with the second field, and when the routingtable has the route entries having the identical interfaceidentifications, updating routing information of the route entry torouting information of the received routing information packet, but whenthe routing table does not have route entries with the identicalinterface identifications, designating the interface value of the secondrouter to a received interface identification and generating a routeentry using the routing information of the received routing informationpacket.
 5. The method according to claim 1, wherein an interior gatewayprotocol is used for a routing protocol between the first router and thesecond router.
 6. The method according to claim 1, wherein a routinginformation protocol for next generation is used for a routing protocolbetween the first router and the second router.
 7. The method accordingto claim 1, wherein the first field is a metric designation field, andthe second field is a prefix field.
 8. The method according to claim 7,wherein at least one of values in a range of 17 to 255 is used as afield value for the metric designation field.
 9. The method according toclaim 7, wherein 255 is used as a field value for the metric designationfield.
 10. A network, comprising: a first router designating apredetermined value to a first field of a route entry, and designatingan interface identification to a second field, accommodating agenerating of routing information, and a routing information packetincluding the routing information being transmitted to a second router;and the second router connected to the first router, extracting a firstfield value of the received routing information packet from the firstrouter and when the extracted field value is the predetermined value, asecond field value is extracted therefrom, and updating routinginformation of a route entry having an interface identificationidentical with the extracted second field value to routing informationof the received routing information packet, and the first and secondrouters being connected to a plurality of hosts.
 11. The networkaccording to claim 10, further comprised of: the first router extractingan interface identification from interface information, the first routerdesignating the predetermined value to the first field of the routeentry, the first router designating the extracted interfaceidentification to the second field of the route entry, generating arouting information packet including the first field with thepredetermined value, the second field with the designated interfaceidentification, and routing information, and the first routertransmitting the generated routing information packet to the secondrouter.
 12. A method, comprising: determining, by a receiving router,whether a first field value of the route entry is a predetermined valueupon receiving a packet of a routing protocol; performing, by areceiving router, the process of the existing routing protocol when thefirst field value is not the predetermined value; extracting, by thereceiving router, a second field value and deciding whether there existsa routing table having the same interface identification when the firstfield value is the predetermined value, where the interfaceidentification of a source router has been designated to a second field;updating routing information of a route entry having an interfaceidentification identical with the second field value extracted torouting information of the received routing information package.
 13. Themethod according to claim 12, wherein the interface identificationdesignated to the second field is generated using a media access controladdress.
 14. The method according to claim 13, further comprised of:extracting, at the receiving router, the interface identification fromthe interface information; designating, at the receiving router, thepredetermined value to the first field of the route entry; designating,at the receiving router, the extracted interface identification to thesecond field of the route entry; generating a routing information packetincluding the first field with the predetermined value, the second fieldwith the designated interface identification, and routing information;and transmitting, at the receiving router, the generated routinginformation packet to the source router.
 15. The method according toclaim 14, wherein the updating of the routing table further comprisesof: deciding whether the routing table has a route entry having aninterface identification identical with the second field, and when therouting table has the route entries having the identical interfaceidentifications, updating routing information of the route entry torouting information of the received routing information packet, but whenthe routing table does not have route entries with the identicalinterface identifications, designating the interface value of the sourcerouter to a received interface identification and generating a routeentry using the routing information of the received routing informationpacket.
 16. The method according to claim 15, wherein an interiorgateway protocol is used for the routing protocol between the sourcerouter and receiving router.
 17. The method according to claim 15,wherein a routing information protocol for next generation is used forthe routing protocol between the source router and the receiving router.18. The method according to claim 15, wherein the first field is ametric designation field, and the second field is a prefix field. 19.The method according to claim 18, wherein at least one of values in arange of 17 to 255 is used as the field value for the metric designationfield.
 20. The method according to claim 18, wherein 255 is used as thefield value for the metric designation field.